2 layers243.2 × 106 mm
2 layers38.5 × 37.5 mm
USB Keyboard 32U4
willybilly31/MicroKeyATmega32U4-AU based micro controller with the sole purpose of emulating keyboard and mouse input.
- Size
- 38.5 × 37.5 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 26
- Nets
- 44
- Pads
- 116
- Tracks, vias
- 181, 29
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 18 Sep 2026
- Updated
- 25 Oct 2026
Overview
USB Keyboard 32U4 is an open-source printed circuit board by willybilly31, from the willybilly31/MicroKey repository on GitHub. It is a 2-layer board of 38.5 × 37.5 mm with 26 parts on 44 nets, routed with 181 tracks and 29 vias.
It is built around the ATMEGA32U4-AU. Its parts include 10 capacitors, 8 resistors, 2 diodes, 2 connectors and 1 IC. It belongs with the keyboards and input boards and the AVR (ATmega, ATtiny) boards of this library.
Main components
1README
README.mdMicroKey
ATmega32U4-AU based micro controller with the sole purpose of emulating keyboard and mouse input. This project was made for Hack Club forge. The idea came to me when i was playing with my Esp32-S3 and thought the keyboard emulation with HID was cool, but the form factor of the Esp32 was too big and i also wanted to make my own devboard and thought this would be simple.
Hardware
- ATmega32U4-AU
- Power Led
- User input Led
- USB C receptacle
- 16mhz Crystal
- Generic 2x3 header for bootloader
Features
- HID emulation with the ATmega32U4-AU
- User input light
Screenshots
BOM
| Designator | Footprint | Quantity | Value | LCSC Part # | Minimum Price | LCSC Link |
|---|---|---|---|---|---|---|
| C1, C2 | 0603 | 2 | 27pF | C1656 | 0.60$ | C1656 |
| C10, C3, C4, C5, C6, C9 | 0603 | 6 | 100nF | C1591 | 0.28$ | C1591 |
| C7 | 0603 | 1 | 10uF | C19702 | 0.40$ | C19702 |
| C8 | 0603 | 1 | 1uF | C15849 | 0.87$ | C15849 |
| D1 | 0603 | 1 | RED | C2286 | 0.0076$ | C2286 |
| D2 | 0603 | 1 | BLUE | C965807 | 0.0043$ | C965807 |
| J1 | GCT_USB4105-GF-A | 1 | USB_C_Receptacle_USB2.0_16P | C5184243 | C5184243 | |
| J2 | AVR_ISP_2x3_Pogo_3p23x1p80 | 1 | Conn_02x03_Odd_Even | |||
| R1, R2 | 0603 | 2 | 5.1k | C23186 | 0.12$ | C23186 |
| R3, R4 | 0603 | 2 | 22 | C23345 | 0.0018$ | C23345 |
| R5, R6 | 0603 | 2 | 1k | C21190 | 0.06$ | C21190 |
| R7, R8 | 0603 | 2 | 10k | C25804 | 0.09$ | C25804 |
| U1 | TQFP-44_10x10mm_P0.8mm | 1 | ATmega32U4-A | C44854 | 6.94$ | C44854 |
| Y1 | Crystal_SMD_3225-4Pin_3.2x2.5mm | 1 | 16MHz | C70562 | 0.55$ | C70562 |
Parts
26| Qty | Value | Footprint | References |
|---|---|---|---|
| 6 | 100nF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C3, C4, C5, C6, C9, C10 |
| 2 | 10k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R7, R8 |
| 2 | 1k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R5, R6 |
| 2 | 22 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R3, R4 |
| 2 | 27pF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2 |
| 2 | 5.1k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2 |
| 1 | 10uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C7 |
| 1 | 16MHz | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | 1uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C8 |
| 1 | ATmega32U4-A | Package_QFP:TQFP-44_10x10mm_P0.8mm | U1 |
| 1 | BLUE | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D2 |
| 1 | Conn_02x03_Odd_Even | MicroKey_Local:AVR_ISP_2x3_Pogo_3p23x1p80 | J2 |
| 1 | Keyboard_Lucide_10mm_Silkscreen | MicroKey_Local:Keyboard_Lucide_10mm_Silkscreen | GKB1 |
| 1 | LOGO | MicroKey_Local:MicroKey_Logo | mii |
| 1 | RED | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D1 |
| 1 | USB_C_Receptacle_USB2.0_16P | Custom Footprints:GCT_USB4105-GF-A | J1 |
Questions
How big is the USB Keyboard 32U4 PCB?
It measures 38.5 × 37.5 mm and has 2 copper layers, 1.6 mm thick.
What parts does the USB Keyboard 32U4 use?
26 parts, built around the ATMEGA32U4-AU. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the USB Keyboard 32U4 KiCad files?
From the willybilly31/MicroKey repository on GitHub, at the commit this page was made from: the board is USB_Keyboard_32U4/USB_Keyboard_32U4.kicad_pcb and its schematic USB_Keyboard_32U4/USB_Keyboard_32U4.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the USB Keyboard 32U4 design in my own project?
Its repository states no licence, so its author keeps all rights: ask willybilly31 before reusing the design.
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